1. Field of the Invention
This invention relates to apparatus for enclosing areas of bodies of water so as to prevent oil or other floating chemicals from escaping said areas.
2. Description of the Prior Art
As the need for liquid hydrocarbon fuels increases, there is greater activity in securing petroleum oil from offshore wells. Also, oil is being transported by tankers of large size over ever lengthening routes, causing the total quantity of oil afloat enroute from source to market to be of great magnitude. Offshore oil-producing operations together with the oil afloat in vessels present a significant threat to the ecology of the sea, against which no truly effective defense has yet been devised.
Systems capable of easy deployment and retrieval to preventively enclose an offshore well or spill area are urgently required. Any successful means for corralling floating oil must be promptly deployable, and capable of confining the oil, even during heavy wave action, until it can be pumped off. Suitable corralling devices must be stored in a compact state upon oil platforms, tankers and skimmer ships.
There is considerable prior art concerning devices which form a floating enclosure. A number of such devices utilize inflatable members having pendant structures. However, many prior devices are more concerned with the thin layer oil slicks on calm water than thick layer spills in open ocean.
Oil containment devices of continuous length have been constructed of pliable material throughout their length, and therein achieve wave profile adaptability. These normally have flexible elongated float means that serve as a surface barrier. A pendant sub-surface curtain barrier of pliable material serves to prevent eddy currents from carrying oil under the barrier. The flexibility of continuous curtain barriers permits conformation to waves, but also allows the bottom of the barrier to balloon out and allow oil pass underneath. Such escape of oil occurs due to currents and when the confining device is being used as a towed collection boom. The flexibility of the float means is limited, and necessarily prevents full adaptation of the barrier to wave profile in heavy waters. This results in wave action lifting the barrier above the surface of troughs between waves and permits underneath escape of oil. In addition, the freeboard of curtain type barriers is limited to the height of the float means, so that oil can splash over the top. Larger floats on rigid pontoons can be used, of course, but these further decrease flexibility of the barrier.
Some earlier oil-confining devices have been of non-inflatable, rigid design, particularly adapted to shallow water conditions, which do not present the problems encountered in deeper waters and rougher seas. Representative devices of such nature are disclosed in U.S. Pat. Nos. 3,494,132; 3,503,512; 3,537,587; 3,592,005; 3,592,007; and 3,592,008.
Still other prior art devices have been comprised of a multiplicity of rigid panels joined in a manner to permit articulated vertical movement and pivotal horizontal movement between adjacent panels. Such devices have require complex assembly under rough sea conditions. The time taken to deploy such devices allows significant spreading of an oil slick while the assembly process takes place. In fact, many of these devices, such as disclosed in U.S. Pat. No. 3,751,925, must be assembled in advance and towed in a vertical disposition to the location of a spill. Although it is designed for rough sea conditions, it would be difficult or impossible to tow such an assembled structure of a length capable of encircling a large spill through rough seas. Many such devices have pivotal joints between barriers which permit leakage of spilled oil through the barrier. Oil confining devices of this type often do not allow for the adjustability of wall height, and therefore may not be rapidly adapted to varying sea conditions and depths of oil spill.
Furthermore, multiple panel devices are expensive to produce and are heavy and cumbersome in nature. For example, a single wall panel as disclosed in U.S. Pat. No. 3,783,662 can weigh as much as 18,400 pounds. It is unlikely that even a large attending ship or oil rig could carry enough panels of this nature to encircle a spill of significant size. Panels such as those disclosed in U.S. Pat. No. 4,033,137 require the precise vertical alignment of panels in order to properly assemble and deploy the device. The handling of such panels on the open sea would certainly require a crane.
It is therefore an object of the present invention to provide an oil confining device which is flexible, light in weight and amenable to storage in a compact yet easily deployable state.
It is another object of the present invention to provide a device of the aforesaid nature which may be rapidly deployed and stored under a variety of weather and sea conditions with minimal manpower and without the use of heavy cranes.
It is another object of the present invention to provide a device of the aforesaid nature which is continuous in nature, having no articulating or pivotal joints.
It is yet another object of the present invention to provide a device of the aforesaid nature which is adjustable in freeboard height and depth and will not deform due to wave action or otherwise permit oil to pass beneath.
It is still another object of the present invention to provide a device of the aforesaid nature of rugged, durable construction amenable to low cost manufacture.
These objects and other objects and advantages of the invention will be apparent from the following description.